Dual-Pump Liquid Additive Delivery Unit for Precise Dosing
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Solution Overview
Problem
Existing delivery units for liquid additives in internal combustion engines face challenges such as high costs, imprecision in dosing, vulnerability to freezing temperatures, and the presence of air bubbles, which affect their reliability and functionality, especially in diesel engines using aqueous urea solutions like AdBlue.
Innovation Solution
A dual-pump system with separate line systems, where the first pump ensures precise dosing through a feed device with an electromagnetically controlled injector, and the second pump handles purging and air bubble removal, with a filter and pulsation damper to prevent air ingress and manage pressure fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pump system is used for liquid additive delivery, then the device complexity is reduced, but the dosing precision and reliability deteriorate
Solution Approach 1:
The delivery unit is divided into two separate pump systems (first pump and second pump) with distinct functions. The first pump is dedicated to precise dosing of liquid additive through a feed device, while the second pump handles purging and air bubble removal. This segmentation allows each pump to be optimized for its specific function, thereby improving dosing precision without unnecessarily complicating the overall system.
2Device complexity
If a single line system is used for liquid additive circulation, then the device complexity is reduced, but the ability to separate dosing and purging functions deteriorates
Solution Approach 1:
The line system is segmented into three separate systems: a first line system connecting the first pump to the feed device for dosing, a second line system connecting the second pump to the tank for purging, and a third line system providing alternative circulation paths. This segmentation enables independent operation of dosing and purging functions, improving functional reliability while maintaining manageable system complexity.
3Device complexity
If air bubbles are present in the delivery unit, then the device complexity remains simple, but the dosing precision and function deteriorate
Solution Approach 1:
The second pump is configured to perform preliminary purging action to remove air bubbles from the liquid additive before it reaches the first pump and feed device. This preliminary removal of air bubbles ensures that the dosing process is not compromised, maintaining high dosing precision without requiring complex bubble detection or removal mechanisms during the dosing operation itself.
4Productivity
If the delivery unit operates quickly after start-up, then the productivity is improved, but the risk of air bubbles and freezing damage increases
Solution Approach 1:
The system performs preliminary purging operations through the second pump before initiating full dosing operations through the first pump. This preliminary action ensures that air bubbles are removed and the system is ready for immediate productive operation, enabling quick start-up while maintaining operational reliability by preventing air bubble interference during dosing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a cost-effective, precise, and robust delivery of liquid additives, ensuring reliable operation at low temperatures and preventing air bubbles, enabling efficient dosing and purging without interrupting regular delivery operations.
Implementation Method 1
the first pump serves merely to build up a predefined pressure of the liquid additive in the first line system, and the precise dosing of the liquid additive is then performed through the use of the feed device which has, for example, an injector operated in an electromagnetically controlled manner
Implementation Method 2
with a filter and pulsation damper to prevent air ingress
Implementation Method 3
with a filter and pulsation damper to prevent air ingress and manage pressure fluctuations
Data Source
AI summary
A delivery unit for a liquid additive includes a first pump with a first suction port and a first pressure port, a second pump with a second suction port and a second pressure port, and a feed device. The feed device is connected to the first pressure port through a first line system and the first suction port is connected to a tank for the liquid additive through a second line system. The second pressure port is connected to the tank through a third line system and the second line system and the third line system are separated from one another. A method for operating a delivery unit and a motor vehicle having a delivery unit are also provided.